单项选择题
The development of（）led to the fully automatic ARPA systems installed on commercial ships.
A.SeaTalk B.powerful microprocessors and mega memory capacity C.chartplotter D.small-scale chart
单项选择题 The（）has a built-in world map; most areas are displayed on a scale of 4000 nm from the top to the bottom of the screen，and can be zoomed in to 150 nm.
单项选择题 Radar reflectors are required for（）.
单项选择题 PPI is（）.
